Structural fracture mechanics is the field of
structural engineering
Structural engineering is a sub-discipline of civil engineering in which structural engineers are trained to design the 'bones and muscles' that create the form and shape of man-made structures. Structural engineers also must understand and cal ...
concerned with the study of load-carrying structures that includes one or several failed or damaged components. It uses methods of analytical
solid mechanics
Solid mechanics, also known as mechanics of solids, is the branch of continuum mechanics that studies the behavior of solid materials, especially their motion and deformation under the action of forces, temperature changes, phase changes, and ...
, structural engineering,
safety engineering
Safety engineering is an engineering discipline which assures that engineered systems provide acceptable levels of safety. It is strongly related to industrial engineering/systems engineering, and the subset system safety engineering. Safety eng ...
,
probability theory
Probability theory is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expressing it through a set ...
, and
catastrophe theory to calculate the load and stress in the structural components and analyze the safety of a damaged structure.
There is a direct analogy between
fracture mechanics of solid and structural fracture mechanics:
There are different causes of the first component failure:
#
mechanical overload,
fatigue (material)
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts o ...
, unpredicted scenario, etc.
# “human intervention” like unprofessional behavior or a terrorist attack.
There are two typical scenarios:
#A localized failure does NOT cause immediate collapse of the entire structure.
#The entire structure fails immediately after one of its components fails.
If the structure does not collapse immediately there is a limited period of time until the catastrophic
structural failure of the entire structure. There is a critical number of structural elements that defines whether the system has reserve ability or not.
Safety engineers use the failure of the first component as an indicator and try to intervene during the given period of time to avoid the catastrophe of the entire structure. For example, “Leak-Before-Break”
Applicability of the leak before break concept. Report of the IAEA Extrabudgetary Programme on the Safety of WWER-440 Model 230 Nuclear Power Plants, 1993
/ref> methodology means that a leak will be discovered prior to a catastrophic failure of the entire piping system occurring in service. It has been applied to pressure vessels, nuclear piping, gas and oil pipelines, etc.
The methods of structural fracture mechanics are used as checking calculations to estimate sensitivity of a structure to its component failure.
The failure of a complex system with parallel redundancy can be estimated based on probabilistic properties of the system elements.
See also
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References
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Structural engineering
Continuum mechanics
Fracture mechanics
Solid mechanics